I don't think it's just the Yellowstone area. In Jasper I've seen bears doing the same sort of the rock-flipping scavenging. The sheer number of moths they eat

I don't think it's just the Yellowstone area. In Jasper I've seen bears doing the same sort of the rock-flipping scavenging. The sheer number of moths they eat is pretty surprising though, I never would have suspected bugs to be such a big food source for bears.